The present invention relates generally to the field of seating and in particular to a chair in which the seat and seat back move in concert to provide a reclining position for the user.
There is an ever-present need for economical and temporary seating space that is typically satisfied by the provision of low cost stackable chairs. The use of low to moderate cost stacking chairs is well known in the art. However, such chairs are designed not with comfort or ergonomics in mind, but rather to provide a large quantity of temporary seats for occasional use, which can ordinarily be stored and take up minimal storage space.
Recent years have brought a growing interest in the development of such chairs based on ergonomic designs intended to promote a sitting posture with a maximum of comfort. One aspect of comfort is the ability to adjust the back of the chair to suit the user. Unfortunately, most stacking chairs do not provide any adjustment capabilities and the ones that do merely provide limited flexibility in the seat back portion with little ergonomic benefit. On the other hand, home and office chairs have been produced in a variety of ergonomic designs that have mechanisms for moving the backs of the chairs into a reclining position.
Chairs featuring the ability to adjust for certain preferences of the user relating to seat height, reclining range, and the like are also well known in the art. These features are accompanied by complexity of manufacture and require the use of expensive and complicated mechanisms that are cumbersome or awkward to adjust and may be subject to malfunction. Such chairs are not suitable for stacking nor use for temporary seating.
In the prior art, U.S. Pat. No. 5,944,382 to Ambasz features a chair providing movement of both the seat and seat back. The Ambasz chair features a slideable seat and also a moveable seat back. There is a separate lumbar section between the seat bottom and the seat back making a three-part seat assembly. The seat bottom has a pair of sockets that fit over seat supporting portions of the seat frame to allow the seat bottom to slide forward and aft. The seat back slides up and down and also tilts to the rear to recline. The seat back is mounted on an articulated linkage that includes springs between the seat back and the upper portion of the linkage to bias the seat back in the upward position. Bellows members connect the seat bottom and the lumbar section and the seat back together. The Ambasz design typifies the complexity and expense of most ergonomic chair designs. Moreover, the Ambasz chair does not lend itself to stacking for storage.
One attempt to marry ergonomics with economics is shown in U.S. Pat. No. RE36,335 to Perry, which discloses a chair having a flexible frame to achieve partial reclining of the seat back. The seat back interconnects the ends of a continuous chair frame with one end projecting upward from the rear legs to the seat back and the other projecting upward from the rear of the seat to the seat back. This two-point connection to the seat back along with curved frame members through the seat back allows limited pivoting of the seat back and also limits pivoting of the seat back. The chair is stackable but of limited comfort, lacking the natural feel provided in a chair having coordinated movement between the seat and seat back.
A need has remained for a chair combining the benefits ergonomic design in a low cost and stackable chair.
Briefly describing one aspect of the invention, a chair featuring a movable seat bottom and seat back is provided. The seat bottom and seat back move in concert between an upright position and a reclined position. The chair includes a frame having a seat bottom support portion and a seat back support portion. In one embodiment, the seat bottom support portion includes a pair of side support members on which the seat bottom is slidably supported. The seat back support portion includes a transverse member to which the seat back is pivotably connected. In one aspect of the invention, this pivotable connection can be accomplished by a plurality of hooks that are preferably molded into the seat back.
The seat bottom and seat back are connected to each other in a manner that allows the seat bottom to slide forward and the seat back to recline in response to the natural forward movement of the seated user""s pelvis along with pressure on the seat back from the user. With this feature, the pivotable connection of the seat back to the support frame allows the frame to act as a fulcrum. Specifically, as force is applied to an upper portion of the seat back, the back pivots about the frame, thereby exerting a force on the seat bottom, causing the bottom to slide along the seat bottom support.
In a preferred embodiment, the seat bottom and seat back are most preferably a one-piece molded plastic shell having a resilient intermediate portion interconnecting the seat bottom and seat back. The intermediate portion operates primarily as a deformable and resilient hinge. Secondarily, the resilient intermediate portion can act as a force transmitting element that translates the pivoting movement of the seat back into a fore and aft force on the seat bottom. The natural characteristics of the plastic shell causes it to rebound to the original position without the use of any mechanical devices as the user brings herself back to the non-reclined position or rises out of the chair.
In certain features, the resilient intermediate portion forms a slack region that exhibits a first curvature when the seat is in an original, non-reclined orientation. When the user reclines, the seat back pivots, the seat bottom slides, and the intermediate slack region deforms to a different second curvature. The resilient intermediate region is configured to allow the user to easily recline the seat by leaning back against the pivotable seat back, while the seat back maintains support for the user""s back at any angle of recline.
The invention further contemplates the use of rail members and slide blocks to effect sliding of the seat bottom. In one preferred aspect, the upper portions of multiple slide blocks are integral with the underside of the seat bottom. Lower portions of the slide blocks can be combined to form a channel slidably surrounding a corresponding one of the rail members. Stops can be provided at opposite ends of the rail members to limit the fore and aft movement of the seat bottom relative to the seat frame.
In one embodiment of the invention, the chair is provided with legs configured to facilitate stacking, while still retaining the pivoting seat back and sliding seat bottom features. In an alternative embodiment, the chair can be provided with a castered pedestal base for ease of movement. Similarly, the chair can be provided with or without arms. In certain armchair versions, the arms project from the back frame at a slight outward angle and with a slight curvature to provide a comfortable seating experience for the user.
Accordingly, it is one object of the invention to provide an ergonomic chair of relatively simple construction, without mechanical springs or lever devices, and at a reasonable cost. Another object is achieved by features of the invention that allow a user to easily recline the chair while the seat back maintains support for the user""s back.
Another object of the invention is to provide a chair with a one-piece molded shell that can be not only reclined, but also easily stacked when not in use. These and other objects, advantages and features are accomplished according to the devices and assemblies, and methods of the present invention.